Invar relay



' March 14, 1933. w. M. ELLINGSON 1,901,708

INVAR RELAY Filed Nov. 11, 1931 2 Sheets-Sheet l 4 Fi 1 F1 2. 5/

INVENTOR WzZlZ'a/72 M EZZZ'Ngsorz.

ATTORNEY March 14, I933- W.M. ELLINGSON 1,901,708

INVAR RELAY Filed Nov. 11, 1931 2 Sheets-Sheet 2 /00 200 300 400 5170600 700 500' 900 man 7, of Motor Rating. WITNESSES: INVENTOR Wz'ZZz'am MEZZmgs'orz.

ATTORNEY Patented Mar. 14 1933 UNITED STATES PATENT OFFICE WILLIAM H.ELLINGSON, F FARGO, NORTH DAKOTA, ASSIGNOR '10 WESTINGHOUSE ELECTRIC 8oMANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA I INVAR RELAYApplication filed November 11, 1931. Serial No. 574,317.

My invention relates to relays and particularly to thermal relays.

An Object of my invention is to provide means in a thermal relay to varythe value 0f the v current at which the relay will operate. 1 I

' My invention is particularly applicable to a thermal relay of the-typeutilizing a member having a thermally-variable magnetic reluctanceheated in accordance with the relay current and embodying also anenergizing coil and a flux-carrying structure including fixed andmovable elements. The

fixed element includes two spaced portions,

the movable element extending therebetween, whereby two.parallel-related flux paths are provided in a certain part of the totalmagneticcircuit. My invention provides a magneticmember of relativelysmall area of cross-section extending from the I movable member towardsone of the spaced elements, and an adjusting means associated therewith.i

While I have illustrated and will describe my invention'as associatedwith and applied to a specific form of thermal relay, I desire it to beunderstood that all of those details not specifically claimed herein areshown and described in a copending application, Serial No. 593,994,filed February 19, 1932, by W. J. Hudson and assigned to theWestinghouse Electric & Manufacturing Company. As already stated, myinvention relates more particularly to adjusting means for a relay ofthe kind disclosed and claimed in the other application.

In the drawings,

' Figure 1 is a view in vertical lateral section through a device withWhich-the elements particularly embodying my invention are associated,

Fig. 2 is a view mainly in front elevation thereof,

Fig. 3 is a. view mainly in side elevation of the elements mostparticularly characteristic of my invention,

Figs. 4 to 10, inclusive, are views either in bottom plan or in sideelevation, of modified forms of devices embodying my invention, and

. Fig.711 is a setof curves illustrating the results obtained by the useof my invention.

Referring to Figs. 1 and 2, I have there illustrated a base plate" 16which is pref: erably made of electric-insulating material and on whichthere is sup 'orted a tubular magnetic core '17 as by a achine bolt 18extending into it and through the base 16.

An energizing coil may consist of two series-connected portions 19 and21, each including a plurality of turns made up of a copper strip orstrap bent on edge-in such manner as to include downwardly de pendingend portions 22 and 23 whose outer ends are connected to and supportedby terminal studs24 and 26 in a manner well known in p the art. Theother end portions of the energizing coil sections are located above thecoil, one end portion 27 extending horizontally forwardly ofor from thebase 16, while the other end'portion 28 extends toward I the front ofthe base, the upper surfaces of: the end portions 27 and 28 beinglocated in the same horizontal. plane and spaced apart in order toreceive and support a connecting strip 29 of a metal or alloy which hasa. thermally variable magnetic reluctance. Such a material may beconstituted by a nickel steel having approximately 36% of nickel,usually called Invar which material is normally magnetic but loses itsmagnetic characteristic at a temperature of about 240 C'. The strip 29may be secured to the ends of the coil sections by any suitable means,such as bolts 31, which are not shown in Fig. 2 of the drawings for thesake of simplicity.

A rear frame 32 of magnetic material and of substantially L'-shape maybe provided,

as well as a front frame 33 also of magnetic material, both the rear andfront frames being held in proper operative positions relatively to thecore 17 by the inclusion of a tubular spacer 34 of electric-insulatingmaterial and by the use of a clamping bolt 36 at the front end of thecore 17, together with suitable washers 37. Y A sliding bracket 38 isadjustably secured to the upper end of the front frame 33 as is setforth in the copending application vhercinbefore referred to andsupports a movable element or armatur'e'39 at one end thereof. Alocating pin 41 is fixed in the sliding bracket 38 and extends into arecess in the forward end of armature 39, a second fixed pin 42 beingfitted, into the sliding bracket 38 and surrounded'by a biasing spring43 to bias the armature 39 downwardly toward the strip or bar 29.

I with a striker plate 48 which may be secured thereto in vany desiredmanner and which engages a vertically extending push rod 49, the upperend of which is adapted to engage a biased switch bar 51 which isresilis ently supported at one end thereof on a contact block 52, themovable end normally engaging a second contact block or terminal 53, themovement of switch arm 51 controlling a circuit in a manner well knownin the art.

.A reset push button 54 is provided and. is

located in a cover plate 56 so that, by turning the same, the push rodmay either be permitted to move upwardly and downwardly or its downwardmovement may be arreste'dafter an upward movement.

It will be noted that the structure hereinbefore described provides afiux carrying path which may be said to start atthe core member 17,extend through the front frame 33, the bracket 38 and the armature 39 ina single path, carrying substantially all of the flux but providing twoparallel-related flux paths from the inner end of the armature to theother portion or part of the frame structure and more particularly therear frame 16 and the apron 44. As shown more particularly in Fig. 1 ofthe drawings, by the heavy broken line 57 a certain part of the fluxwill traverse the air gap between the upper surface of the armature 39and the forwardly extending part of rear frame 32, while the rest of theflux will normally traverse a downwardly extending lockout pin 61 ofmagnetic material, one end of which may be secured'in the armature 39,while the other end extends toward the apron 44 and more particularlytoward the mid portion of strip 29. The flux traversing the member orlockout pin, 61 will flow in part through the normally magnetic strip 29as long as it is magnetic, as well as through the forwardly eX- tendingportion of apron 44 and from there into the vertical part of rear frame32 through which it then may flow to the core member 17 It is, ofcourse, obvious that, under all conditions of operation, the ampereturns for the two parallel related flux paths will be the same, butthere will be a difference in the amount of flux lines traversing therespective parallel related aths under diflerent current conditions 0the relay itself. 1

In order to provide adjusting means by which the distance between thelock-out pin 61 and invar strip 29 may be varied, I ro-' vide anadjusting nut 62 on in 61 w ich has a relatively large annular ange 63having a plurality of recesses 64 therein en gageab e by a machine screw66 which may extend through armature 39 in the manner shown particularlyin Figs. 1 and 3 of the drawings. Fig. 3 illustrates a position ofadjusting nut 62 in which the lower end oflock-out pin 61 is in directengagement with strip 29 so that the magnetic reluctance between thelock-out pin and strip29 is a.

minimum.

' Referring to Fig. 4 of the drawin s, I have there shown the use 'ofaresl ient spring latch 65, one end of which is mounted on armature 39and the other end which engages a selected recess 64.

Referring to Fig. 5 of the drawings, I

have there illustrated a modified form of adjusting means including,more particularly, a non-magnetic stud 67 extending upwardly fromarmature 39 through the fore wardly extending portion of rearframe 32and held in an adjusted position by a plurality of nuts 68 which arepreferably made of non-magnetic material.

Referring to Fig. 6 of the drawings, I have there illustrated anothermodification of an adjusting means including a bell crank,

lever 69 of non-magnetic material pivotallyi mounted in a lug 70 securedto rear frame 32. One end of lever 69 engages the lower face of armature39, while the other end thereof is provided with a suitable adjustingscrew 71 and a lock nut 72, all made of nonmagnetic material.

Referring to Fig. 7 of the drawings, 1

have there shown another modification of an adjusting device including alever 73 of substantially S-shape whose mid point may be pivotallymounted in the armature 39, the lower'end portion extending below thearmature and engaging the strip 29, while the other end portion islocated abovethe armature 39 and is provided with an adjusting screw'74, members 73 and 74 both being preferably made of non-magneticmaterial.

Referring to Fig. 8, I have there illustrated another modification inwhich an adjusting screw 76 of non-magnetic matetends therethrough andis locked in any position by a lock nut 79.

Referring to Fig. 10, a lock-out pin 81 of magnetic material may bewelded or otherwise secured to the armature 39 and engage an adjustablestud 82 of non-magnetic material, whose position in the strip 29 is heldby a lock nut 83. While I have illustrated a number of modificationsdisclosingv means for adjusting the position of the lock-out inrelatively to the strip of material havmg a thermally variable magneticreluctance, it is obviousthat other modifications of these variousstructures may be employed so long as they make it possible to adjustthe position of the look-out pin easily and quickly.

Let it be assumed that the energy transv lating device, such as anelectric motor, is

traversed by a current corresponding to the normal-load which may beconsidered as be ing'100%. It is, of course, desirable that the thermalrelay operatively associated with the motor shall not operate todeenergize the motor by suitable means well known in'the art so-long asthe motor is not overloaded. The use of a bar or strip 29 which isheated in accordance with the current traversing the relay and alsotraversing the motor ensures that the relay will operate after the relayand the motor have been traversed by an over-load current of apredetermined value for a predetermined length of time, which len h oftime is necessary to efiect heatin o the strip 29 to a temperature whichwill cause ity to lose its magnetic characteristic. When this conditionoccurs, in arelay ofthe types shown in the drawings, it is obvious, ofcourse, that the reluctance of one of the parallel-related paths willhave been changed, that is, 'increased by reason of the change of themagnetic condition of the-strip 29 to a nonmagnetic condition. It isfurther obvious that the pull-in tor ue attendant upon the flux flowingfrom t e armature 39 to the.

forwardly extending end portion of frame 32.will be increased and theresultant up- -ward pull will be suflicient to effect movement ofarmature 39, which movement may be utilized to control the circuit of anactuatin coil of a suitable contactor or circuit brea er controlling themotor circuit.

It may also be noted that an excessive overload current traversing therelay and the armature will result in increasing the flux density in themagnetic circuit and particularly in the area of the look-out in 61.

It is, further, obvious that a value-o vmotor operation of the relay witcurrent will soon be reached at which the relatively large and whoselength is rela-' tively small, so that a ain movement of the armature 39will be e 'ecte'd, thismovement being independent of any variation inthe magnetic reluctance of the strip 29. We

thus obtain operation of thezrelay with a time delay in the case ofmoderate overloads and instantaneously in the case of excessiveoverloads.

The device more particularly embodying my invention is incorporated in athermal relay of this type to permit of varying the current value atwhich operation 0 the relay will be eflected. Reference to Fig. llof thedrawings will show three curves 91, 92 and 93 illustrating the operationof a relay with different settings of the lock-out pin relatively to themagnetically reversible strip 29. Curye 91 illustrates the operation ofa relay embodyin my invention when the outer end of. the lock-out pinnormally actually engages the strip 29. Curve 92 illustrates the actionof the relay with a small air gap and curve 93 illustrates the actionwith a somewhat larger .air

ap. Referring first to curve 91, it is tonoted that it will require amotor current corre 29- will remain substantially at room 'temperaturewhich, in the case of the particular set of tests illustrated in Fig.11, is 40 C. If a current be caused to traverse the motor correspondingto 5 times normal current, the relay will operate with a time delaywhich will permit the armature of the magnetically reversible strip 29to reach a little over 200 C, so that it will still be magnetic but notto as great a degree as if its temperature were much lower. For thesame-curve 91, a motor load of 125% would cause heating of the strip tosubstantially 240 C. whereby it would become non-ma netic and cause.

time delay, and it is to be understood that this time delay will be suchas the motor itself can withstand, that is, for such va length of timeas the motor can carry 125% of normal load without dangerous overheat-1n 2 teferring now to curve 92, it will be noted that instantaneousactuation of the an appreciable I relay will be effected with 600% ofnormal I load and that it will equire a much longer time for aotuation othe relay with a 300% load, which load will heat the strip 29 to atemperature of about 215. When a large air gap is used between thelook-out pin and the magnetically reversible strip, instantaneousoperation of the relay will be efl'ected at 300% of normal full load.The use of the device more particularly embodying my invention asapplied to a relay of this general kind makes it possible to fullyprotect a motor against overload currents and 'the range of operation ofsuch a relay is, as will be noted from the curves of Fig. 11, relativelywide and as there shown, from 300% to 1000% of normal load currentvalue. It is, therefore, possible to meet any ordinar and probably alsoextraordinary operating conditions by' the use of a relay of this kindequipped with a device particularly embodying my invention.

Various modifications may be made in the device embodying my inventionwithout departing from the spirit and scope thereof and I desire,therefore, that only such limitations shall, be placed thereon as areimposed by the prior art or .are set forth. in the appended claims; Iclaim as my invention: 1. A thermal relay including a source ofmagneto-motive force, a fiuxcarrying structure therefor including amovable armature, said structure providing two parallel related fluxpaths and means for manually varying the reluctance of one of saidparallel related 'flux paths.

2. A thermal relay including a source of magneto-motive force, aflux-carrying structure comprising fixed and relatively movable parts,said structure providing two parallel related flux paths between amovable and a fixed part, and manual means for varying the reluctance ofone of said parallel related flux'paths.

3. A thermal relay including an energizing coil, a fixed magnetizableframe structure embodying two spaced portions, a movable magne'tizablemember extending between said spaced portions, a magnetic element, ofrelatively small area of cross section extendingfrom the movablemagnetizas ble member toward one of said spaced portions to provideaflux path therebetween,

said spaced portion embodying a magnetically reversible element heatedin accordance with the relay current to vary the magnetic reluctance andeffect movement of the movable member.

4; A device as set forth in claim 3 in which the magnetic element ofrelatively small area of cross section is supported by the movablemagnetizable tween it and the magnetically reversible element.

6. A thermal relay comprising a currenttraversed energizing coil, aflux-carrying structure associated with the coil and including a fixedportion embodyingtwo spaced elements and a portion extendingtherebetween and movable relatively thereto, and means extending fromthe movable portion toward one of the spaced elements causing.

movement of the movable portion at a prede- WILLIAM M. ELLINGSON.

